Umm, thanks, but no thanks...
I think that this is the dumbest idea ever, but I have a few friends that swear by it. Two social networks, CouchSurfing and AirBed & Breakfast, offer beds in the houses of volunteers. Basically, you sign up to be a host, and then say yes or no to people who ask to come stay with you.
I haven't seen the movie 'Hostel', but I've seen the previews, and they are scary enough to turn me away from this idea. Even if your host doesn't want to maim, murder or rob you, what if their couch smells bad? Or they smell bad? Or they make really gross food and you feel obliged to eat it? I could keep going, but instead I'll just keep paying for hotels.